Many industrial processes, of which glass making is illustrative, require appreciable quantities of B.sub.2 O.sub.3 as an ingredient in a composition that is to be melted at relatively high temperatures in a furnace. The B.sub.2 O.sub.3 may be supplied by many different borate compounds. The following is a list of some of the more readily available borate compounds:
______________________________________ Mineral or Chemical Name Chemical Formula ______________________________________ Boric acid H.sub.3 BO.sub.3 Anhydrous boric acid B.sub.2 O.sub.3 Anhydrous borax Na.sub.2 O . 2B.sub.2 O.sub.3 5 Mol borax Na.sub.2 O . 2B.sub.2 O.sub.3 . 5H.sub.2 O Borax Na.sub.2 O . 2B.sub.2 O.sub.3 . 10H.sub.2 O Dehydrated Rasorite Na.sub.2 O . 2B.sub.2 O.sub.3 Probertite Na.sub.2 O . 2CaO . 5B.sub.2 O.sub.3 . 10H.sub.2 O Ulexite Na.sub.2 O . 2CaO . 5B.sub.2 O.sub.3 . 16H.sub.2 O Colemanite 2CaO . 3B.sub.2 O.sub.3 . 5H.sub.2 O Calcined colemanite 2CaO . 3B.sub.2 O.sub.3 . H.sub.2 O Sodium Perborate NaBO.sub.2 . H.sub.2 O.sub.2 . 3H.sub.2 O ______________________________________
Because of the disadvantages of relatively large amounts of water or soda in many of these compounds, a large potential demand for pure calcium borates exists. Colemanite and especially calcined colemanite are desirable for glass making processes particularly where compacting glass batch is employed.